Post-processing.
For the baseline video representation, we apply the same post-processing strategy as in [1]}, [2]}, i.e., the representation vector of a video is first \(l_2\) -normalized, and then whitened using PCA [3]} and \(l_2\) -normalized again. For the imprint descriptors on the video imprint, power normalization (\(\alpha =0.2\) ) shows better results than \(l_2\) -normalization in our experiments. Therefore, after feature alignment, the imprint descriptors are first power normalized, then PCA-whitened and \(l_2\) -normalized.
